Electricity price seasonality in France may be shifting. This summer, average temperatures were 3.7°C above seasonal norms. These heatwaves drove up demand, largely due to the increased use of cooling systems. We therefore estimate France’s summer demand sensitivity to temperature at 870 MW/°C for 2026, up from 790 MW/°C in 2025.
⚛️ Nuclear generation: record losses due to environmental constraints in 2026
Environmental constraints resulted in nearly 9 TWh of lost nuclear generation in France. High temperatures and low river flow rates forced Électricité de France (EDF) to reduce the output of certain reactors to comply with environmental limits. Despite these restrictions, the impact on France’s electricity balance remains contained for now: the country maintained an average net export of 10.5 GW between mid-June and mid-August.
⛲ Hydroelectric generation: historically low levels
2026 has been marked by a precipitation deficit across mainland France. Hydroelectric reservoir levels were also low, sitting 35% below 2024 levels.
💹 Flexibility needs: unmistakable signals
Several market indicators point to an increased need for flexibility: day-ahead price spreads were wider this summer than in winter, as were prices for system services. Without new capacity capable of rapidly responding to fluctuations in demand and generation, gas-fired power plants could see increased utilization during summer peaks. Batteries, pumped-storage hydropower (PSH), and demand-side management will therefore play an increasingly important role in shifting energy over time and limiting reliance on the most expensive thermal generation assets.
Summer could thus gradually cease to be the French power system’s low-demand season, instead becoming a period characterized—in its own right—by strain, volatility, and the monetization of flexibility.
Electricity: Heading towards summers that are consistently more expensive and volatile
